Rubble cleaner for bottom hole formation tester



1957 J. E. WALSTROM RUBBLE CLEANER FOR BOTTOM HOLE FORMATION TESTER Filed March 27, 1956 INVENTOR JO/ZVpEfiLS OM- V ATORNEY S 4 b I H L .2 I F United State ate RUBBLE CLEANER FOR BOTTOM HOLE FORMATION TESTER John E. Walstrom, Orinda, Califl, assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware Application March 27, 1956, Serial No. 574,118

3 Claims. (Cl. 166-63) The present invention relates to formation testers and more particularly to a seating arrangement for a bottom hole formation tester wherein the tool is adapted to seat directly on the bottom of a full-diameter bore hole.-

It is a particular object of the present invention to provide apparatus for clearing rubble from the bottom of a full-diameter bore hole to assure a firm, fluid-tight seal between a formation tester and the formation lying directly ahead of the well bore, to permit the formation to be perforated by an explosive without permitting bore hole fluid to enter the tester sample chamber.

In accordance with a preferred form of the invention, a rotatable bottom hole seal is resiliently supported on the lower end of the tester body and rotatable therewith. Preferably the bottom-engaging face of a resilient packer member is formed to centrifugally remove rubble from the bottom of the well bore when the tester body is rotated. The upper end of resilient packer is further arranged to come into firm contact with a sealing plate at the bottom of the tester body and contacts directly the perforating means that opens the tester body and the bottom of the well bore to permit fluid to enter from the formation directly at the bottom of the bore hole.

The present application is directed to an improved method of seating a bottom hole formation tester of the type disclosed in my application Serial No. 413,006, filed March 1, 1954. As therein disclosed, an open-hole formation tester is supported on the lower end of a section of dry, or partially full, drill pipe. The formation tester has a diameter substantially the same as the drill pipe; both pipe and tester diameters are substantially smaller than the bore hole. The lower end of the formation tester is sealed to maintain the pipe and the tester body dry until after the tester is seated on bottom. An explosive, such as a shaped charge located directly behind a closure plate is exploded to open the seal. In this arrangement, the lower end of the testing tool is seated directly on the bottom of the well bore. A resilient packer is formed on the bottom of the tool and the weight of the drill pipe increased to complete a pack-oflf against the hydrostatic pressure of bore hole fluid. At times this packing off of the tool may fail so that drilling fluid, always under about 500 pounds greater pressure than formation fluid, enters the tool and spoils the test. Rubble, consisting of broken bits of rock, sand and the like, accumulating on bottom during drilling, may be the cause of this drilling fluid leakage into the tester. Thus, removal of rock fragments between the true bottom of the well bore and the bottom seal makes possible a fluidtight seal between the bottom packer face and the undisturbed rock at the bottom of the Well bore. Additionally, with a better seal, the carrot-like hole, formed when the explosive is set ofi, penetrates deeper into the formation under test.

In accordance with the present invention, the bottom hole formation tester is provided with a resilient packer member having a plurality of deformable blades. Said fluid pressure in formations along the well bore.

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packer member is rotatable so that upon rotation thereof fragments of rock, sand and the like are expelled from that portion of the well bore directly ahead of the packer. Preferably the rotatable blades are formed as an integral part of the bottom hole packer, and the packer is springloaded to contact the bottom of the well bore ahead of the tester tool; subsequently, the packer is retracted by an increase of the weight on the drill pipe and the tester body. Such increase in load brings the packer into firm contact with the back-up plate which seals the tester and forms a portion of the shaped charge device.

Further objects and advantages of the present invention will become apparent from the following detailed description taken together with the accompanying drawing, which forms an integral part of the present specification.

In the drawing,

Fig. 1 is a side elevation view of the tester body, broken away in its lower portion to show in section the rubblecleaning arrangement of the present invention;

Fig. 2 is a view similar to the lower end of Fig. 1, which illustrates the seating of the packer on bottom, just prior to ignition of the explosive to open the tester and penetrate the formation (as shown in phantom) at the bottom of the well bore;

Fig. 3 is a cross-sectional plan view taken in the direction of arrows 33 in Fig. l; and

Fig. 4 is a bottom plan view of the tool .illustrated in Fig. 1.

Referring now to the drawing and in particular to Fig. 1, there is illustrated a tester body 10 adapted to be supported on the lower end of a stand of drill pipe 11. Drill pipe 11 is in turn supported from the earths surface by a drill derrick which desirably includes a weight control system for the pipe. As disclosed in my said copending application, drill pipe 11 is maintained dry on the inside and the lower portion of tester body 10 includes a firing mechanism (not shown in the present arrangement) which terminates in a section of prima cord 12 arranged to explode shaped charge 13 after the tester body has been seated directly on bottom of a full-diameter well bore 15.

In the seating of tester body 10 on bottom, rubble, such as rock chips, indicated generally as 14, at the bottom of well bore 15 frequently interferes with the proper seating of the packer member, indicated in the present embodiment as 17. The success or failure of the bottom hole formation test, wherein shaped charge 13 sequentially perforates back-up or closure plate 18 and the bottom of well bore 15, depends upon the adequacy of the seal against the excessive pressure of bore hole fluid 16. As indicated above, drilling fluid 16 is normally maintained at a pressure of about 500 p. s. i. greater than any potential Thus the drilling fluid is at a considerably higher pressure than any fluid contained in formation 20 lying directly at the bottom of the well bore.

For the purpose of cleaning the bottom of the well bore in accordance with the present invention, packer member 17 has formed on its lower end a plurality of blade means 21. As shown in Fig. 4, blades 21 are curved in form so that upon counter-clockwise rotation of the drill pipe 11, tester body 10, and blades 21, rubble or other loose fragments are cleaned from the bottom of the well bore. Since Fig. 4 is a bottom plan view of packer 17, the actual direction of rotation of drill pipe 11 will, of course, be clockwise.

In the present arrangement packer means 17 and blades 21 are preferably rotated through a. guide means including the four keys 23, equally spaced around the circumference of packer support 25. Keys 23 in turn drivingly engage four keyways 27 formed in a sleeve member 29 extending below and forwardly of bottom sealing plate 18. Packer member 17 is urged forwardly in sleeve member 29 by spring means 31. Desirably fluid-equalizing ports 33 are formed around the circumference of sleeve member 29 to prevent hydrostatic pressure from building up on either side of packer member 17.

From the foregoing description it will be apparent that upon touching bottom with the tester, drill pipe 11 will be suitably rotated at the surface to turn blades 21. Rubble will thus be cleaned from the formation directly ahead of tester 10.

As such cleaning operation proceeds, the weight on the drill pipe is increased so that the end of sleeve member 29 comes into contact with formation 20. Preferably, but not necessarily, the lower end of sleeve member 29 may be provided with a cuttingedge 35 formed by beveled member 39 on the leading edge of sleeve 29. This lead end of sleeve 29 may be formed with small cutting surfaces or have embedded therein diamond dust, carbide particles or the like. In this way the sleeve member may cut into the undisturbed rock directly ahead of the well bore, as illustrated in Fig. 2. It will be seen in Fig. 2 that as sleeve 29 enters the formation, packer member 17 retracts within said sleeve so that upper end 37 of packer 17 comes into flush engagement with plate 18. As illustrated further in Fig. 2, wiper blades 21 are preferably formed of material soft enough so that these blades are deformed to some extent within sleeve 29. Thus, packer 17 forms a nearly solid seal between the bottom of well bore 15 and sealing plate 18. When shaped charge 13 is detonated, plate 18 and packer 17 are perforated sequentially to open a characteristic carrot-like hole (shown in phantom) into formation 20. In this way there is provided a fluid flow pathway into the interior of tester body 10 and pipe 11. The fluid pressure in this passageway is maintained at a pressure not much greater than atmospheric and thus substantially below that of drilling fluit 16. Hence any fluid in formation 21) may readily rise through the opening formed in packer 17 and plate 13 for the taking of the desired sample.

Replacement of packer 17 within support 25 may be accomplished by forming said support in two sections. Additionally, shaped charge 13, back-up plate 18 and packer member 17 may be readily assembled for subsequent tests by removal of pins 40 holding beveled member 39 on the lower end of sleeve 29.

While not illustrated in the drawings, there is, of course, provided a suitable valving arrangement for sealing off the bottom of tester 10 prior to withdrawal of fluid and the tester from the well bore. Additional valve means are provided for equalizing pressures on opposite sides of packer 17 so that the tool may be readily withdrawn from bottom.

While various modifications and changes in the particular form of the packer member and in the driving connection between the tester body and the packer member will occur to those skilled in the art, all such modifications and changes falling within the scope of the appended claims are intended to be included therein.

I claim:

1. The combination with a bottom hole formation fluid tester body member having a fluid-receiving chamber and a lower sealed end adapted to be supported on the lower end of a rotatable string of drill pipe to engage the bottom of a bore hole, valve means for opening and closing said fluid receiving chamber to admit and entrap formation fluids therein, and means for forming a passageway through said lower sealed end to connect said valve means to said bottom of said bore hole, of bottom hole packer arrangement for clearing fragments of rocl: from the central portion ofthe bottom of the bore hole and sealing said lower sealed end of said tester body to the bottom of said bore hole, said packer arrangement comprising a sleeve member connected to and extending beyond said sealed end of said tester body member, a packer support member mounted in said sleeve member and axially movable relative thereto, a packer element having an external diameter substantially less than the diameter of the well bore mounted in said packer support member, at least a portion of said packer element normally extending beyond the end of said sleeve member, radial blade means formed in the lower face of said extending portion of said packer element, drive means between said packer support memberand said sleeve member for rotating said packer support member and said packer element with said sleeve member and spring means for urging said blade means and said packer element beyond the end of said sleeve member, said spring means permitting said packer element to retract along said sleeve member to bring said packer element into said sealing engagement between said sealed end of said tester body member and the cleared central portion of said bore hole, whereby said passageway forming means carried by said tester body member forms a passageway through said lower sealed end and said packer arrangement, said passageway extending from said fluid-receiving chamber to the bottom of the bore hole.

2. The combination with an open-borehole formation tester body member adapted to be run into a bore hole on a rotatable string of drill pipe, said tester body member having an axially extending sample-receiving chamber formed in said body member and a lower sealed end portion adapted to be seated on bottom in the bore hole for sampling fluid in a formation lying directly at the bottom of a full-diameter bore hole, and including formation perforating means positioned in the bottom of said samplereceiving chamber, of apparatus for removing drill chips and other rubble from the bottom of the bore hole to permit said lower end of said sample chamber of said tester to be sealed against the pressure of bore hole fluid comprising a sleeve member secured to and extending beyond said sealed end of said sample-receiving chamber, a packer member axially movable relative to said sleeve member, said packer member having an external diameter substantially less than the diameter of the well bore and at least the lower end face portion of said packer member extending beyond the end of said sleeve member, radial blade means formed in said lower end face of said extending portion of said packer member, drive means for rotating said blade means including guide means interfitting between said packer member and said sleeve member to permit said packer member to move axially relative to said sleeve member but non-rotatable thereto so that said packer member may be retracted during rota tion of said sleeve member by said tester body and said drill pipe, and spring means for urging said packer member toward the end of said sleeve member, stop means limiting said movement of said packer member, said spring means permitting said packer member to retract along said sleeve member when the weight on said tester body is increased to bring said packer member into firm engagement between said sealed end of said tester body and the cleared central portion of the bottom of said bore hole.

3. The combination with a formation tester body member adapted to be supported in a bore hole on the lower end of a rotatabie drill string for sampling fluid in a formation lying directly at the bottom of an uncased bore hole having an undiminished diameter, said tester body member including a sample-receiving chamber having a sealed lower end and perforating means associated therewith to form an opening into said chamber to admit fluid from an earth formation at the bottom of said bore hole, of apparatus for clearing rubble such as sand, silt, and rock fragments from the central portion of the bottom and permitting the lower end of said tester body member to be sealed on bottom so that fluid under less hydrostatic pressure than the bore hole fluid :may enter said samplereceiving chamber ,of =said tester, .said apparatus comprising a packer means having an external diameter substantially less than the diameter of said well bore but substantially larger than the opening formed between the bore hole bottom and said sample-receiving chamber when said perforating means pierces the said chamber and the bottom of the bore hole, radial blade means formed on the lower end face of said packer member, and means for rotating said packer member when said tester body is rotated by said drill string including sleeve means connected to said tester body and extending beyond the end thereof to reciprocably support said packer means, key and keyway means interfitting between said packer means and said sleeve means so that said packer means is reciprocable but non-rotatable relative to said sleeve, coil spring means for urging said packer means away from the lower end of said tester body member and toward the lower end of said sleeve means, one end of said spring means being mounted in an annular recess radially outwardly of said lower sealed end of said sample receiving chamber and the other end being mounted in a similar recess formed in one side of said packer means so that said lower end face of said tester body member, adjacent the opening into said sample-receiving chamber, is in firm engagement with said packer means and the opposite side of said packer means is in firm engagement with the cleared central portion of the bottom of said well bore in sample position.

References Cited in the file of this patent UNITED STATES PATENTS 1,347,534 Cox July 27, 1920 2,171,000 Iden Aug. 29, 1939 2,220,989 Brauer Nov. 12, 1940 

